upstream-man-pages/man2/glXChooseFBConfig.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="glXChooseFBConfig">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glXChooseFBConfig</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glXChooseFBConfig</refname>
  17         <refpurpose>return a list of GLX frame buffer configurations that match the specified attributes</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>GLXFBConfig * <function>glXChooseFBConfig</function></funcdef>
  23                 <paramdef>Display * <parameter>dpy</parameter></paramdef>
  24                 <paramdef>int <parameter>screen</parameter></paramdef>
  25                 <paramdef>const int * <parameter>attrib_list</parameter></paramdef>
  26                 <paramdef>int * <parameter>nelements</parameter></paramdef>
  27             </funcprototype>
  28         </funcsynopsis>
  29     </refsynopsisdiv>
  30     <!-- eqn: ignoring delim $$ -->
  31     <refsect1 id="parameters"><title>Parameters</title>
  32         <variablelist>
  33         <varlistentry>
  34             <term><parameter>dpy</parameter></term>
  35             <listitem>
  36                 <para>
  37                     Specifies the connection to the X server.
  38                 </para>
  39             </listitem>
  40         </varlistentry>
  41         <varlistentry>
  42             <term><parameter>screen</parameter></term>
  43             <listitem>
  44                 <para>
  45                     Specifies the screen number.
  46                 </para>
  47             </listitem>
  48         </varlistentry>
  49         <varlistentry>
  50             <term><parameter>attrib_list</parameter></term>
  51             <listitem>
  52                 <para>
  53                     Specifies a list of attribute/value pairs.
  54                     The last attribute must be <constant>None</constant>.
  55                 </para>
  56             </listitem>
  57         </varlistentry>
  58         <varlistentry>
  59             <term><parameter>nelements</parameter></term>
  60             <listitem>
  61                 <para>
  62                     Returns the number of elements in the list returned by <function>glXChooseFBConfig</function>.
  63                 </para>
  64             </listitem>
  65         </varlistentry>
  66         </variablelist>
  67     </refsect1>
  68     <refsect1 id="description"><title>Description</title>
  69         <para>
  70             <function>glXChooseFBConfig</function> returns GLX frame buffer configurations that match the attributes
  71             specified in <parameter>attrib_list</parameter>, or <constant>NULL</constant> if no matches are found.
  72             If <parameter>attrib_list</parameter> is <constant>NULL</constant>, then <function>glXChooseFBConfig</function> returns an array of GLX
  73             frame buffer configurations that are available on the specified screen.
  74             If an error occurs, no frame buffer configurations exist on the
  75             specified screen, or if no frame buffer configurations match the
  76             specified attributes, then <constant>NULL</constant> is returned.
  77             Use <function>XFree</function> to free the memory returned by
  78             <function>glXChooseFBConfig</function>.
  79         </para>
  80         <para>
  81             All attributes in <parameter>attrib_list</parameter>, including boolean attributes, are
  82             immediately followed by the corresponding desired value. The list is
  83             terminated with <constant>None</constant>. If an attribute is not specified in <parameter>attrib_list</parameter>,
  84             then the default value (see below) is used (and the attribute is said to be
  85             specified implicitly). For example, if <constant>GLX_STEREO</constant> is not specified, then
  86             it is assumed to be <constant>False</constant>. For some attributes, the default is
  87             <constant>GLX_DONT_CARE</constant>, meaning that any value is OK for this attribute, so the
  88             attribute will not be checked.
  89         </para>
  90         <para>
  91             Attributes are matched in an attribute-specific manner.
  92             Some of the attributes, such as <constant>GLX_LEVEL</constant>, must match the specified
  93             value exactly; others, such as, <constant>GLX_RED_SIZE</constant> must meet or exceed the
  94             specified minimum values. If more than one GLX frame buffer configuration is found,
  95             then a list of configurations, sorted
  96             according to the ``best'' match criteria, is returned. The match
  97             criteria for each attribute and the exact sorting order is
  98             defined below.
  99         </para>
 100         <para>
 101             The interpretations of the various GLX visual attributes are as follows:
 102         </para>
 103         <variablelist>
 104             <varlistentry>
 105                 <term><constant>GLX_FBCONFIG_ID</constant></term>
 106                 <listitem>
 107                     <para>
 108                     </para>
 109                     <para>
 110                         Must be followed by a valid XID that indicates the desired GLX frame
 111                         buffer configuration. When a <constant>GLX_FBCONFIG_ID</constant> is specified, all
 112                         attributes are ignored. The default value is <constant>GLX_DONT_CARE</constant>.
 113                     </para>
 114                 </listitem>
 115             </varlistentry>
 116             <varlistentry>
 117                 <term><constant>GLX_BUFFER_SIZE</constant></term>
 118                 <listitem>
 119                     <para>
 120                     </para>
 121                     <para>
 122                         Must be followed by a nonnegative integer that indicates the desired
 123                         color index buffer size.
 124                         The smallest index buffer of at least the specified size is preferred.
 125                         This attribute is ignored if <constant>GLX_COLOR_INDEX_BIT</constant> is not set in
 126                         <constant>GLX_RENDER_TYPE</constant>. The default value is 0.
 127                     </para>
 128                 </listitem>
 129             </varlistentry>
 130             <varlistentry>
 131                 <term><constant>GLX_LEVEL</constant></term>
 132                 <listitem>
 133                     <para>
 134                     </para>
 135                     <para>
 136                         Must be followed by an integer buffer-level specification.
 137                         This specification is honored exactly.
 138                         Buffer level 0 corresponds to the default frame buffer of the display.
 139                         Buffer level 1 is the first overlay frame buffer, level two the second
 140                         overlay frame buffer, and so on.
 141                         Negative buffer levels correspond to underlay frame buffers.
 142                         The default value is 0.
 143                     </para>
 144                 </listitem>
 145             </varlistentry>
 146             <varlistentry>
 147                 <term><constant>GLX_DOUBLEBUFFER</constant></term>
 148                 <listitem>
 149                     <para>
 150                     </para>
 151                     <para>
 152                         Must be followed by <constant>True</constant> or <constant>False</constant>. If
 153                         <constant>True</constant> is specified, then
 154                         only double-buffered frame buffer configurations are considered;
 155                         if
 156                         <constant>False</constant> is specified, then
 157                         only single-buffered frame buffer configurations are considered.
 158                         The default value is <constant>GLX_DONT_CARE</constant>.
 159                     </para>
 160                 </listitem>
 161             </varlistentry>
 162             <varlistentry>
 163                 <term><constant>GLX_STEREO</constant></term>
 164                 <listitem>
 165                     <para>
 166                     </para>
 167                     <para>
 168                         Must be followed by <constant>True</constant> or <constant>False</constant>. If
 169                         <constant>True</constant> is specified, then
 170                         only stereo frame buffer configurations are considered;
 171                         if
 172                         <constant>False</constant> is specified, then
 173                         only monoscopic frame buffer configurations are considered.
 174                         The default value is <constant>False</constant>.
 175                     </para>
 176                 </listitem>
 177             </varlistentry>
 178             <varlistentry>
 179                 <term><constant>GLX_AUX_BUFFERS</constant></term>
 180                 <listitem>
 181                     <para>
 182                     </para>
 183                     <para>
 184                         Must be followed by a nonnegative integer that indicates the desired
 185                         number of auxiliary buffers.
 186                         Configurations with the
 187                         smallest number of auxiliary buffers that meet or exceed
 188                         the specified number are preferred.
 189                         The default value is 0.
 190                     </para>
 191                 </listitem>
 192             </varlistentry>
 193             <varlistentry>
 194                 <term><constant>GLX_RED_SIZE</constant>, <constant>GLX_GREEN_SIZE</constant>, <constant>GLX_BLUE_SIZE</constant>, <constant>GLX_ALPHA_SIZE</constant></term>
 195                 <listitem>
 196                     <para>
 197                     </para>
 198                     <para>
 199                         Each attribute, if present, must be followed by a nonnegative minimum size
 200                         specification or <constant>GLX_DONT_CARE</constant>.
 201                         The largest available total RGBA color buffer size (sum of <constant>GLX_RED_SIZE</constant>,
 202                         <constant>GLX_GREEN_SIZE</constant>, <constant>GLX_BLUE_SIZE</constant>, and <constant>GLX_ALPHA_SIZE</constant>)
 203                         of at least the minimum size specified for each color component is preferred.
 204                         If the requested number of bits for a color component is 0 or
 205                         <constant>GLX_DONT_CARE</constant>, it is not considered. The default value for each color
 206                         component is 0.
 207                     </para>
 208                 </listitem>
 209             </varlistentry>
 210             <varlistentry>
 211                 <term><constant>GLX_DEPTH_SIZE</constant></term>
 212                 <listitem>
 213                     <para>
 214                     </para>
 215                     <para>
 216                         Must be followed by a nonnegative minimum size specification.
 217                         If this value is zero,
 218                         frame buffer configurations with no depth buffer are preferred.
 219                         Otherwise, the largest available depth buffer of at least the minimum size
 220                         is preferred.
 221                         The default value is 0.
 222                     </para>
 223                 </listitem>
 224             </varlistentry>
 225             <varlistentry>
 226                 <term><constant>GLX_STENCIL_SIZE</constant></term>
 227                 <listitem>
 228                     <para>
 229                     </para>
 230                     <para>
 231                         Must be followed by a nonnegative integer that indicates the desired
 232                         number of stencil bitplanes.
 233                         The smallest stencil buffer of at least the specified size is preferred.
 234                         If the desired value is zero,
 235                         frame buffer configurations with no stencil buffer are preferred.
 236                         The default value is 0.
 237                     </para>
 238                 </listitem>
 239             </varlistentry>
 240             <varlistentry>
 241                 <term><constant>GLX_ACCUM_RED_SIZE</constant></term>
 242                 <listitem>
 243                     <para>
 244                     </para>
 245                     <para>
 246                         Must be followed by a nonnegative minimum size specification.
 247                         If this value is zero,
 248                         frame buffer configurations with no red accumulation buffer are preferred.
 249                         Otherwise, the largest possible red accumulation buffer
 250                         of at least the minimum size is preferred.
 251                         The default value is 0.
 252                     </para>
 253                 </listitem>
 254             </varlistentry>
 255             <varlistentry>
 256                 <term><constant>GLX_ACCUM_GREEN_SIZE</constant></term>
 257                 <listitem>
 258                     <para>
 259                     </para>
 260                     <para>
 261                         Must be followed by a nonnegative minimum size specification.
 262                         If this value is zero,
 263                         frame buffer configurations with no green accumulation buffer are preferred.
 264                         Otherwise, the largest possible green accumulation buffer
 265                         of at least the minimum size is preferred.
 266                         The default value is 0.
 267                     </para>
 268                 </listitem>
 269             </varlistentry>
 270             <varlistentry>
 271                 <term><constant>GLX_ACCUM_BLUE_SIZE</constant></term>
 272                 <listitem>
 273                     <para>
 274                     </para>
 275                     <para>
 276                         Must be followed by a nonnegative minimum size specification.
 277                         If this value is zero,
 278                         frame buffer configurations with no blue accumulation buffer are preferred.
 279                         Otherwise, the largest possible blue accumulation buffer
 280                         of at least the minimum size is preferred.
 281                         The default value is 0.
 282                     </para>
 283                 </listitem>
 284             </varlistentry>
 285             <varlistentry>
 286                 <term><constant>GLX_ACCUM_ALPHA_SIZE</constant></term>
 287                 <listitem>
 288                     <para>
 289                     </para>
 290                     <para>
 291                         Must be followed by a nonnegative minimum size specification.
 292                         If this value is zero,
 293                         frame buffer configurations with no alpha accumulation buffer are preferred.
 294                         Otherwise, the largest possible alpha accumulation buffer
 295                         of at least the minimum size is preferred.
 296                         The default value is 0.
 297                     </para>
 298                 </listitem>
 299             </varlistentry>
 300             <varlistentry>
 301                 <term><constant>GLX_RENDER_TYPE</constant></term>
 302                 <listitem>
 303                     <para>
 304                     </para>
 305                     <para>
 306                         Must be followed by a mask indicating which OpenGL rendering modes
 307                         the frame buffer configuration must support.
 308                         Valid bits are <constant>GLX_RGBA_BIT</constant> and
 309                         <constant>GLX_COLOR_INDEX_BIT</constant>. If the mask is
 310                         set to <constant>GLX_RGBA_BIT</constant> | <constant>GLX_COLOR_INDEX_BIT</constant>,
 311                         then only frame buffer configurations that can be bound to both
 312                         RGBA contexts and color index contexts will be considered.
 313                         The default value is <constant>GLX_RGBA_BIT</constant>.
 314                     </para>
 315                 </listitem>
 316             </varlistentry>
 317             <varlistentry>
 318                 <term><constant>GLX_DRAWABLE_TYPE</constant></term>
 319                 <listitem>
 320                     <para>
 321                     </para>
 322                     <para>
 323                         Must be followed by a mask indicating which GLX drawable types
 324                         the frame buffer configuration must support. Valid bits are
 325                         <constant>GLX_WINDOW_BIT</constant>,
 326                         <constant>GLX_PIXMAP_BIT</constant>, and <constant>GLX_PBUFFER_BIT</constant>.
 327                         For example, if mask is set to
 328                         <constant>GLX_WINDOW_BIT</constant> | <constant>GLX_PIXMAP_BIT</constant>,
 329                         only frame buffer configurations that support both windows and GLX pixmaps
 330                         will be considered.
 331                         The default value is <constant>GLX_WINDOW_BIT</constant>.
 332                     </para>
 333                 </listitem>
 334             </varlistentry>
 335             <varlistentry>
 336                 <term><constant>GLX_X_RENDERABLE</constant></term>
 337                 <listitem>
 338                     <para>
 339                     </para>
 340                     <para>
 341                         Must be followed by <constant>True</constant> or <constant>False</constant>.
 342                         If <constant>True</constant> is specified, then only frame buffer configurations that
 343                         have associated X visuals (and can be used to render to Windows and/or
 344                         GLX pixmaps) will be considered.
 345                         The default value is <constant>GLX_DONT_CARE</constant>.
 346                     </para>
 347                 </listitem>
 348             </varlistentry>
 349             <varlistentry>
 350                 <term><constant>GLX_X_VISUAL_TYPE</constant></term>
 351                 <listitem>
 352                     <para>
 353                     </para>
 354                     <para>
 355                         Must be followed by one of
 356                         <constant>GLX_TRUE_COLOR</constant>,
 357                         <constant>GLX_DIRECT_COLOR</constant>,
 358                         <constant>GLX_PSEUDO_COLOR</constant>,
 359                         <constant>GLX_STATIC_COLOR</constant>,
 360                         <constant>GLX_GRAY_SCALE</constant>, or
 361                         <constant>GLX_STATIC_GRAY</constant>, indicating the desired X visual type.
 362                         Not all frame buffer configurations have an associated X visual. If
 363                         <constant>GLX_DRAWABLE_TYPE</constant> is specified in <parameter>attrib_list</parameter> and the
 364                         mask that follows does not have <constant>GLX_WINDOW_BIT</constant> set,
 365                         then this value is ignored. It is also ignored if
 366                         <constant>GLX_X_RENDERABLE</constant> is specified as <constant>False</constant>.
 367                         RGBA rendering may be supported for visuals of type
 368                         <constant>GLX_TRUE_COLOR</constant>,
 369                         <constant>GLX_DIRECT_COLOR</constant>,
 370                         <constant>GLX_PSEUDO_COLOR</constant>,
 371                         or <constant>GLX_STATIC_COLOR</constant>,
 372                         but color index rendering is only supported for visuals of type
 373                         <constant>GLX_PSEUDO_COLOR</constant> or <constant>GLX_STATIC_COLOR</constant>
 374                         (i.e., single-channel visuals).
 375                         The tokens <constant>GLX_GRAY_SCALE</constant> and <constant>GLX_STATIC_GRAY</constant> will
 376                         not match current OpenGL enabled visuals, but are included for future use.
 377                         The default value for <constant>GLX_X_VISUAL_TYPE</constant> is <constant>GLX_DONT_CARE</constant>.
 378                     </para>
 379                 </listitem>
 380             </varlistentry>
 381             <varlistentry>
 382                 <term><constant>GLX_CONFIG_CAVEAT</constant></term>
 383                 <listitem>
 384                     <para>
 385                     </para>
 386                     <para>
 387                         Must be followed by one of
 388                         <constant>GLX_NONE</constant>,
 389                         <constant>GLX_SLOW_CONFIG</constant>,
 390                         <constant>GLX_NON_CONFORMANT_CONFIG</constant>.
 391                         If <constant>GLX_NONE</constant> is specified, then only frame buffer configurations with
 392                         no caveats will be considered; if <constant>GLX_SLOW_CONFIG</constant>
 393                         is specified, then only slow frame buffer configurations will be considered; if
 394                         <constant>GLX_NON_CONFORMANT_CONFIG</constant> is specified, then only
 395                         nonconformant frame buffer configurations will be considered.
 396                         The default value is <constant>GLX_DONT_CARE</constant>.
 397                     </para>
 398                 </listitem>
 399             </varlistentry>
 400             <varlistentry>
 401                 <term><constant>GLX_TRANSPARENT_TYPE</constant></term>
 402                 <listitem>
 403                     <para>
 404                     </para>
 405                     <para>
 406                         Must be followed by one of
 407                         <constant>GLX_NONE</constant>,
 408                         <constant>GLX_TRANSPARENT_RGB</constant>,
 409                         <constant>GLX_TRANSPARENT_INDEX</constant>.
 410                         If <constant>GLX_NONE</constant> is specified, then only opaque
 411                         frame buffer configurations will be considered; if <constant>GLX_TRANSPARENT_RGB</constant>
 412                         is specified, then only transparent
 413                         frame buffer configurations that support RGBA rendering will be considered;
 414                         if <constant>GLX_TRANSPARENT_INDEX</constant> is specified,
 415                         then only transparent frame buffer configurations that support color
 416                         index rendering will be considered.
 417                         The default value is <constant>GLX_NONE</constant>.
 418                     </para>
 419                 </listitem>
 420             </varlistentry>
 421             <varlistentry>
 422                 <term><constant>GLX_TRANSPARENT_INDEX_VALUE</constant></term>
 423                 <listitem>
 424                     <para>
 425                     </para>
 426                     <para>
 427                         Must be followed by an integer value indicating the transparent
 428                         index value; the value must be between 0 and the maximum
 429                         frame buffer value for indices.
 430                         Only frame buffer configurations that use the
 431                         specified transparent index value will be considered.
 432                         The default value is <constant>GLX_DONT_CARE</constant>.
 433                         This attribute is ignored unless <constant>GLX_TRANSPARENT_TYPE</constant> is
 434                         included in <parameter>attrib_list</parameter> and specified as <constant>GLX_TRANSPARENT_INDEX</constant>.
 435                     </para>
 436                 </listitem>
 437             </varlistentry>
 438             <varlistentry>
 439                 <term><constant>GLX_TRANSPARENT_RED_VALUE</constant></term>
 440                 <listitem>
 441                     <para>
 442                     </para>
 443                     <para>
 444                         Must be followed by an integer value indicating the transparent
 445                         red value; the value must be between 0 and the maximum
 446                         frame buffer value for red.
 447                         Only frame buffer configurations that use the
 448                         specified transparent red value will be considered.
 449                         The default value is <constant>GLX_DONT_CARE</constant>.
 450                         This attribute is
 451                         ignored unless <constant>GLX_TRANSPARENT_TYPE</constant> is included in
 452                         <parameter>attrib_list</parameter> and specified as <constant>GLX_TRANSPARENT_RGB</constant>.
 453                     </para>
 454                 </listitem>
 455             </varlistentry>
 456             <varlistentry>
 457                 <term><constant>GLX_TRANSPARENT_GREEN_VALUE</constant></term>
 458                 <listitem>
 459                     <para>
 460                     </para>
 461                     <para>
 462                         Must be followed by an integer value indicating the transparent
 463                         green value; the value must be between 0 and the maximum
 464                         frame buffer value for green.
 465                         Only frame buffer configurations that use the
 466                         specified transparent green value will be considered.
 467                         The default value is <constant>GLX_DONT_CARE</constant>.
 468                         This attribute is
 469                         ignored unless <constant>GLX_TRANSPARENT_TYPE</constant> is included in
 470                         <parameter>attrib_list</parameter> and specified as <constant>GLX_TRANSPARENT_RGB</constant>.
 471                     </para>
 472                 </listitem>
 473             </varlistentry>
 474             <varlistentry>
 475                 <term><constant>GLX_TRANSPARENT_BLUE_VALUE</constant></term>
 476                 <listitem>
 477                     <para>
 478                     </para>
 479                     <para>
 480                         Must be followed by an integer value indicating the transparent
 481                         blue value; the value must be between 0 and the maximum
 482                         frame buffer value for blue.
 483                         Only frame buffer configurations that use the
 484                         specified transparent blue value will be considered.
 485                         The default value is <constant>GLX_DONT_CARE</constant>.
 486                         This attribute is ignored unless <constant>GLX_TRANSPARENT_TYPE</constant> is included in
 487                         <parameter>attrib_list</parameter> and specified as <constant>GLX_TRANSPARENT_RGB</constant>.
 488                     </para>
 489                 </listitem>
 490             </varlistentry>
 491             <varlistentry>
 492                 <term><constant>GLX_TRANSPARENT_ALPHA_VALUE</constant></term>
 493                 <listitem>
 494                     <para>
 495                     </para>
 496                     <para>
 497                         Must be followed by an integer value indicating the transparent
 498                         alpha value; the value must be between 0 and the maximum
 499                         frame buffer value for alpha.
 500                         Only frame buffer configurations that use the
 501                         specified transparent alpha value will be considered.
 502                         The default value is <constant>GLX_DONT_CARE</constant>.
 503                     </para>
 504                 </listitem>
 505             </varlistentry>
 506         </variablelist>
 507         <para>
 508             When more than one GLX frame buffer configuration matches the specified attributes,
 509             a list of matching configurations is returned. The list is sorted
 510             according to the following precedence rules, which are applied in ascending
 511             order (i.e., configurations
 512             that are considered equal by a lower numbered rule are sorted by the higher
 513             numbered rule):
 514         </para>
 515         <variablelist>
 516             <varlistentry>
 517                 <term>1.</term>
 518                 <listitem>
 519                     <para>
 520                         By <constant>GLX_CONFIG_CAVEAT</constant> where the precedence is <constant>GLX_NONE</constant>,
 521                         <constant>GLX_SLOW_CONFIG</constant>, and <constant>GLX_NON_CONFORMANT_CONFIG</constant>.
 522                     </para>
 523                 </listitem>
 524             </varlistentry>
 525             <varlistentry>
 526                 <term>2.</term>
 527                 <listitem>
 528                     <para>
 529                          Larger total number of RGBA color components
 530                         (<constant>GLX_RED_SIZE</constant>, <constant>GLX_GREEN_SIZE</constant>, <constant>GLX_BLUE_SIZE</constant>,
 531                         plus <constant>GLX_ALPHA_SIZE</constant>)
 532                         that have higher number of bits. If the requested number of bits in
 533                         <parameter>attrib_list</parameter> is zero or <constant>GLX_DONT_CARE</constant> for a particular color
 534                         component, then the number of bits for that component is not considered.
 535                     </para>
 536                 </listitem>
 537             </varlistentry>
 538             <varlistentry>
 539                 <term>3.</term>
 540                 <listitem>
 541                     <para>
 542                         Smaller <constant>GLX_BUFFER_SIZE</constant>.
 543                     </para>
 544                 </listitem>
 545             </varlistentry>
 546             <varlistentry>
 547                 <term>4.</term>
 548                 <listitem>
 549                     <para>
 550                         Single buffered configuration (<constant>GLX_DOUBLEBUFFER</constant> being
 551                         <constant>False</constant> precedes a double buffered one.
 552                     </para>
 553                 </listitem>
 554             </varlistentry>
 555             <varlistentry>
 556                 <term>5.</term>
 557                 <listitem>
 558                     <para>
 559                         Smaller <constant>GLX_AUX_BUFFERS</constant>.
 560                     </para>
 561                 </listitem>
 562             </varlistentry>
 563             <varlistentry>
 564                 <term>6.</term>
 565                 <listitem>
 566                     <para>
 567                         Larger <constant>GLX_DEPTH_SIZE</constant>.
 568                     </para>
 569                 </listitem>
 570             </varlistentry>
 571             <varlistentry>
 572                 <term>7.</term>
 573                 <listitem>
 574                     <para>
 575                         Smaller <constant>GLX_STENCIL_SIZE</constant>.
 576                     </para>
 577                 </listitem>
 578             </varlistentry>
 579             <varlistentry>
 580                 <term>8.</term>
 581                 <listitem>
 582                     <para>
 583                         Larger total number of accumulation buffer color components
 584                         (<constant>GLX_ACCUM_RED_SIZE</constant>, <constant>GLX_ACCUM_GREEN_SIZE</constant>,
 585                         <constant>GLX_ACCUM_BLUE_SIZE</constant>, plus <constant>GLX_ACCUM_ALPHA_SIZE</constant>) that have
 586                         higher number of bits. If the requested number of bits in <parameter>attrib_list</parameter> is
 587                         zero or <constant>GLX_DONT_CARE</constant> for a particular color component, then the
 588                         number of bits for that component is not considered.
 589                     </para>
 590                 </listitem>
 591             </varlistentry>
 592             <varlistentry>
 593                 <term>9.</term>
 594                 <listitem>
 595                     <para>
 596                         By <constant>GLX_X_VISUAL_TYPE</constant> where the precedence order is
 597                         <constant>GLX_TRUE_COLOR</constant>, <constant>GLX_DIRECT_COLOR</constant>, <constant>GLX_PSEUDO_COLOR</constant>,
 598                         <constant>GLX_STATIC_COLOR</constant>, <constant>GLX_GRAY_SCALE</constant>, <constant>GLX_STATIC_GRAY</constant>.
 599                     </para>
 600                 </listitem>
 601             </varlistentry>
 602         </variablelist>
 603     </refsect1>
 604     <refsect1 id="examples"><title>Examples</title>
 605         <para>
 606         </para>
 607         <variablelist>
 608             <varlistentry>
 609                 <term><parameter>attrib_list</parameter> =</term>
 610                 <listitem>
 611                     <para>
 612                         {<constant>GLX_RENDER_TYPE</constant>, <constant>GLX_RGBA_BIT</constant>,
 613                         <constant>GLX_RED_SIZE</constant>, 4,
 614                         <constant>GLX_GREEN_SIZE</constant>, 4,
 615                         <constant>GLX_BLUE_SIZE</constant>, 4,
 616                         <constant>None</constant>};
 617                     </para>
 618                 </listitem>
 619             </varlistentry>
 620         </variablelist>
 621         <para>
 622             Specifies a frame buffer configuration that supports RGBA rendering
 623             and exists in the normal frame buffer,
 624             not an overlay or underlay buffer.
 625             The returned visual supports at least four bits each of red,
 626             green, and blue,
 627             and possibly no bits of alpha.
 628             It does not support stereo display.
 629             It may or may not have one or more auxiliary color buffers,
 630             a back buffer,
 631             a depth buffer,
 632             a stencil buffer,
 633             or an accumulation buffer.
 634         </para>
 635     </refsect1>
 636     <refsect1 id="notes"><title>Notes</title>
 637         <para>
 638             <function>glXChooseFBConfig</function> is available only if the GLX version is 1.3 or greater.
 639         </para>
 640         <para>
 641             If the GLX version is 1.1 or 1.0, the GL version must be 1.0.
 642             If the GLX version is 1.2, then the GL version must be 1.1.
 643             If the GLX version is 1.3, then the GL version must be 1.2.
 644         </para>
 645         <para>
 646             <citerefentry><refentrytitle>glXGetFBConfigs</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glXGetFBConfigAttrib</refentrytitle></citerefentry> can
 647             be used to implement selection algorithms other than the generic
 648             one implemented by <function>glXChooseFBConfig</function>. Call <function>glXChooseFBConfig</function> to retrieve all the frame buffer configurations
 649             on a particular screen or, alternatively, all the frame buffer configurations with
 650             a particular set of attributes. Next, call <citerefentry><refentrytitle>glXGetFBConfigAttrib</refentrytitle></citerefentry>
 651             to retrieve additional attributes for the frame buffer configurations and then
 652             select between them.
 653         </para>
 654         <para>
 655             GLX implementations are strongly discouraged,
 656             but not proscribed,
 657             from changing the selection algorithm used by <function>glXChooseFBConfig</function>.
 658             Therefore, selections may change from release to release
 659             of the client-side library.
 660         </para>
 661     </refsect1>
 662     <refsect1 id="errors"><title>Errors</title>
 663         <para>
 664             <constant>NULL</constant> is returned if an undefined GLX attribute is
 665             encountered in <parameter>attrib_list</parameter>, if <parameter>screen</parameter> is invalid, or if <parameter>dpy</parameter> does
 666             not support the GLX extension.
 667         </para>
 668     </refsect1>
 669     <refsect1 id="seealso"><title>See Also</title>
 670         <para>
 671             <citerefentry><refentrytitle>glXGetFBConfigAttrib</refentrytitle></citerefentry>,
 672             <citerefentry><refentrytitle>glXGetFBConfigs</refentrytitle></citerefentry>,
 673             <citerefentry><refentrytitle>glXGetVisualFromFBConfig</refentrytitle></citerefentry>
 674         </para>
 675     </refsect1>
 676     <refsect1 id="Copyright"><title>Copyright</title>
 677         <para>
 678             Copyright <trademark class="copyright"></trademark> 1991-2006
 679             Silicon Graphics, Inc. This document is licensed under the SGI
 680             Free Software B License. For details, see
 681             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 682         </para>
 683     </refsect1>
 684 </refentry>